A telephone to which an incoming call is directed receives an incoming call signal which includes alternating ringing current intervals and silent intervals. By way of example, each ringing current interval might have a duration in the order of about two seconds, and each silent interval might have a duration in the order of about four seconds. During the ringing current intervals, a current at the receiving telephone activates an indicator which provides an indication of an incoming call, for example by causing an audible ringing tone. During the silent intervals, other information might be transmitted to the receiving telephone at a frequency which does not activate the incoming call indicator. U.S. Pat. No. 4,582,956, the disclosure of which is incorporated herein by reference, shows a method and apparatus for providing information at a telephone during the silent interval between ringing current intervals. One type of information that might be transmitted during the silent intervals is caller identification information which indicates the telephone number of the telephone from which the incoming call originated.
Many, telephones have the ability to respond to the caller identification information by providing an indication of the telephone number of the originating telephone. When the caller identification is indicated in a visual display on the telephone, it is necessary for the person receiving the call to observe that display in order to determine the identity of the calling number. With a cellular telephone, this might involve removing the telephone from a carrying case in order to view the display. With a land line telephone, it might involve going to the telephone to view the display. Even if the person does not wish to answer incoming calls from certain persons or from unknown persons, still it is necessary for him or her to view the telephone display in order to determine whether the call is from someone with whom he or she wishes to talk.
Telephones are available in which a listing of preferred calling numbers is stored, and when a call is received from one of those stored numbers, a unique ringing tone is provided. Thus, each of several preferred calling numbers can have its own unique ringing tone. In order to be distinguishable, there must be a reasonable difference between the several unique ringing tones. Only a limited number of ringing tones are available. Users of telephones, particularly cellular telephones like to have unique and surprising indications of an incoming call. Further, such telephones frequently are able to receive short message service (“SMS”) messages and multimedia messaging service (“MMS”) messages. Users of such telephones like to have unique indications of receipt of those messages.